JACC Adv. 2026 Oct;5(10 Pt 2):103288. doi: 10.1016/j.jacadv.2026.103288.
ABSTRACT
BACKGROUND: Higher total serum IgG levels have been associated with protection from cardiovascular events in ASCOT (Anglo-Scandinavian Cardiac Outcomes Trial). Antibodies against oxidized low-density lipoprotein (LDL) have also been linked to favorable clinical and vascular imaging outcomes.
OBJECTIVES: The aim of this study was to determine whether regular walnut consumption influences circulating immunoglobulins, malondialdehyde-modified LDL (MDA-LDL), a highly immunogenic form of oxidized LDL, and antibodies against MDA-LDL.
METHODS: The Walnuts and Healthy Aging study was a two-center, randomized controlled trial conducted in Spain and the United States. Adults aged 63 to 79 years were assigned to a walnut-enriched diet or a control diet excluding walnuts for 2 years. Serum total immunoglobulin G (IgG), total immunoglobulin M (IgM), MDA-LDL, and IgG and IgM anti MDA-LDL antibodies were measured by enzyme-linked immunoassays in 474 participants.
RESULTS: Baseline immunoglobulin concentrations differed substantially by study center. Participants from the United States had 25% lower total IgM and IgG concentrations than participants from Spain. Walnut consumption increased total serum IgG by 11% in the U.S. cohort (95% CI: 0%-24%; P = 0.040), whereas pooled analysis showed a 6% increase across both cohorts (95% CI: 0%-12%; P = 0.041). Over the 2-year study period, total IgM and both IgG and IgM anti-MDA-LDL concentrations declined significantly in both the control and intervention groups.
CONCLUSIONS: Long-term walnut consumption was associated with a modest increase in total serum IgG but had no significant effect on total IgM, MDA-LDL, or antibodies against MDA-LDL. Baseline IgG and IgM concentrations were substantially lower among U.S. participants, suggesting that geographic, environmental, social, or genetic factors may modulate immune biomarkers independently of dietary intervention.
PMID:42954696 | DOI:10.1016/j.jacadv.2026.103288